Childhood learning potential as an alternative to traditional ability measures.

Hypothesized advantages of Learning Potential (LP) assessments were investigated for kindergartners varying in racial background (Anglo, Black, English-dominant Puerto Rican, Spanish-dominant Puerto Rican). Ss (N?=?209) were randomly assigned to 1 of 3 treatments: LP, test coaching, and test practice. Subsequent to treatments, children were evaluated on 2 standardized criteria of academic achievement, 2 teacher-rated criteria of achievement, and 3 dimensions of learning-related classroom behavior. Research hypotheses anticipated relatively higher posttest scores and improved criterion validity for children in the LP condition. Moreover, it was expected on the basis of LP theory that minority children in the LP condition would display greater score increments than Anglos. Results failed to support any hypothesis. The most notable finding was that a single subtest score from a traditional intelligence test predicted criterion performance as well as the more involved LP posttest score. Implications are discussed in the context of LP testing and current assessment practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

HBED: the continuing development of a potential alternative to deferoxamine for iron-chelating therapy

To further examine the potential clinical usefulness of the hexadentate phenolic aminocarboxylate iron chelator N, N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED) for the chronic treatment of transfusional iron overload, we performed a subchronic toxicity study of the HBED monosodium salt in rodents and have evaluated the iron excretion in primates induced by HBED. The HBED-induced iron excretion was determined for the monohydrochloride dihydrate that was first dissolved in a 0.1-mmol/L sodium phosphate buffer at pH 7.6 and administered to the primates either orally (PO) at a dose of 324 micromol/kg (149.3 mg/kg, n = 5), subcutaneously (sc) at a dose of 81 micromol/kg (37.3 mg/kg, n = 5), sc at 324 micromol/kg (n = 5), and sc at 162 micromol/kg (74.7 mg/kg) for 2 consecutive days for a total dose of 324 micromol/kg (n = 3). In addition, the monosodium salt of HBED in saline was administered to the monkeys sc at a single dose of 150 micromol/kg (64.9 mg/kg, n = 5) or at a dose of 75 micromol/kg every other day for three doses, for a total dose of 225 micromol/kg (n = 4). For comparative purposes, we have also administered deferoxamine (DFO) PO and sc in aqueous solution at a dose of 300 micromol/kg (200 mg/kg). In the iron-loaded Cebus apella monkey, whereas the PO administration of DFO or HBED even at a dose of 300 to 324 micromol/kg was ineffective, the sc injection of HBED in buffer or its monosodium salt, 75 to 324 micromol/kg, produced a net iron excretion that was nearly three times that observed after similar doses of sc DFO. In patients with transfusional iron overload, sc injections of HBED may provide a much needed alternative to the use of prolonged parenteral infusions of DFO. Note: After the publication of our previous paper (Blood, 91:1446, 1998) and the completion of the studies described here, it was discovered that the HBED obtained from Strem Chemical Co (Newburyport, MA) that was labeled and sold as a dihydrochloride dihydrate was in fact the monohydrochloride dihydrate. Therefore, the actual administered doses were 81, 162, or 324 micromol/kg; not 75, 150, or 300 micromol/kg as was previously reported. The new data have been recalculated accordingly, and the data from our earlier study, corrected where applicable, are shown in parentheses.     

Protein targeting to the plant vacuole--a historical perspective

Although many properties of the targeting of plant endomembrane proteins are similar to mammalian and yeast systems, several clear differences are found that will be stressed in this review. In the past few years, we have seen an advancement in our understanding of the signals for vacuolar protein targeting and some insights into the mechanisms of transport to the vacuole in the plant cell. This work will form the basis for elucidation of the fundamental principles that govern protein trafficking through the secretory system to the vacuole.     

Nitric oxide in learning and memory

The role of nitric oxide in the central nervous system is described. The main part of this article concerns the problem of learning and memory.     

Isolated-brain parallels to simple types of learning and memory in Tritonia

Physiological studies of learning and memory often require reduced nervous system preparations that can be trained by stimulation of neural pathways in a manner that mimics behavioral training. In the isolated brain preparation of the seaslug Tritonia, fictive swimming can be activated with a few electrical pulses applied to the cut end of a nerve, and learning experiments can be simulated with combinations of nerve stimuli. Repeated application of a nerve stimulus produced changes in fictive swimming that resembled habituation and iterative enhancement of multiple components of the swimming behavior. Many repetitions of the nerve stimulus led to fictive swimming failure. Stimulation of another nerve then restored the ability of the original nerve to activate fictive swimming, thus reproducing dishabituation results. Sensitization of threshold and latency were also simulated. Parallels between the behavior and the isolated brain suggest that the neuronal modifications underlying simple types of learning can be induced by nerve stimulation. The activity pattern of interneuron C2 in these experiments suggests that increased C2 synaptic efficacy may underlie sensitization of swimming latency.     

Estradiol enhances learning and memory in a spatial memory task and effects levels of monoaminergic neurotransmitters

Calretinin (CaR) is a calcium-binding protein that is distributed extensively in the central nervous system. It is localized in the cell bodies and neurites of specific neuronal populations and serves, therefore, as a reliable anatomical marker. Some components of the pretectocerebellar projection, which connects specific pretectal nuclei to caudal cerebellar folia, are concerned with the cerebellar control of visual reflexes. We investigated the distribution of pretectocerebellar-projecting neurons in relation to cells that show CaR immunoreactivity. Cells that project to the cerebellar cortex in the diencephalic primary visual nuclei and in other grisea, like the nucleus spiriformis medialis and the nucleus dorsofrontalis, colocalized with those that appeared to be immunolabeled intensely with anti-CaR antiserum. To explore the hypothesis of a common developmental origin of these pretectal cerebellopetal neurons, we also investigated the development of CaR-immunopositive cells in the chick pretectum and the arrival of their fibers in the cerebellum, from 10 days of incubation (stage 36) to posthatching stages. Finally, we analyzed the source of CaR+ climbing fibers and found a subpopulation of CaR+ cells in the inferior olivary nucleus. On the whole, these results suggest that there is a common developmental origin of pretectal cerebellopetal neurons, some of which share the property of CaR expression. The functional significance of this correlation needs to be investigated.     

Spatial learning and memory as a function of age in the dog.

Spatial learning and memory were studied in dogs of varying ages and sources. Compared to young dogs, a significantly higher proportion of aged dogs could not acquire a spatial delayed nonmatching-to-sample task. A regression analysis revealed a significant age effect during acquisition. Spatial memory was studied by comparing performance at delay intervals of 20, 70, and 110 s. At short delays aged and young dogs were similar; at longer delays, errors increased to a greater extent in old than in young dogs; however, this was not statistically significant. It was possible to identify 2 groups of aged animals, age-impaired and age-unimpaired. Several of the dogs were also tested on an object recognition memory task, which was more difficult to learn than the spatial task. The possibility that these findings are confounded by breed differences is considered. Overall, the present results provide further evidence of the value of a canine model of aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Protein synthesis and memory: A review.

Reviews studies that have used protein synthesis inhibitors to test the hypothesis that memory in part depends on brain protein synthesis. Evidence from learning curves, examination of short-term retention, and posttraining drug injection indicate that initial acquisition is not dependent on such synthesis, but it appears that protein synthesis, during or shortly after training, is an essential step in the formation of long-term memory. Possible side effects of protein synthesis inhibitors are considered in terms of locomotor activity, abnormal cerebral electrical activity, conditioned aversion, and catecholamine biosynthesis. Stages of memory formation are discussed, and the possibility that kindling, drug tolerance, and enzyme induction are dependent on protein synthesis is considered. (8 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Skill learning in the elderly: Diminished implicit and explicit memory for a motor sequence.

Studied explicit and implicit memory for a cognitive-motor sequence in elderly and young adults. Implicit memory was examined in a serial reaction time (RT) paradigm in which sequences of hand postures repeated cyclically, then shifted to random sequences. Two control groups received random sequences throughout. Movement times (MTs) across the 1st 4 blocks did not improve more in the elderly-repeated than in the elderly-random group. In contrast, the young-repeated group showed greater improvement in MT across these blocks than the young-random group. MT was less affected in the elderly than in the young by shifts between repeated and random sequences, indicating impaired implicit memory. Explicit memory, which was assessed by free recall and cued recall, also was impaired in the elderly. Diminished implicit memory in the elderly could not be explained solely by the possible intrusion of conscious recollection strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preserved learning and memory in amnesia: Intact adaptation-level effects and learning of stereoscopic depth.

Amnesic patients and control Ss performed similarly on 2 memory tests. In experiments 1A and 1B, amnesic patients exhibited intact adaptation-level effects: An experience lifting and judging a group of weights influenced their judgments of a 2nd group of weights 20–25 min later. The effect did not depend on peripheral accommodation, because Ss used 1 hand during their 1st encounter with the weights and the opposite hand during their 2nd encounter. In Experiment 2, amnesic patients acquired at a normal rate the ability to perceive binocular depth using random-dot stereograms. In both experiments, amnesic patients benefited from recent experience, despite the fact that they could not remember their prior experience accurately. The preserved memory abilities demonstrated here appear to be examples of implicit, or nondeclarative, memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two procedures to improve instructional text: Effects on memory and learning.

The goal of this study was to compare 2 approaches for improving instructional text. The first was based on the procedure created by B. K. Britton and S. Gülg?z (1991) as derived from W. Kintsch and T. A. van Dijk's theory (1978). It emphasized the reduction of the reader's inferential activity. We created a second method that was inspired by theories of narrative comprehension (P. van den Broek, 1990; A. C. Graesser, M. Singer, & T. Trabasso, 1994). We oriented it toward triggering causal inferences in the reader. Alternative versions of an original passage on history were elaborated for each of the 2 methods. Sixty-four 8th graders read either the original passage or one of the revised versions and were tested on memory (i.e., recall) and learning (i.e., inference questions). Only the 2nd procedure produced benefits on inferential learning, though both procedures had a limited effect on recall. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Defects of immune cells in the senescence-accelerated mouse: a model for learning and memory deficits in the aged

AM1 and PM3 complete geometry optimizations were performed on 19 arotinoids congeneric with (E)-4-[2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2- naphthalenyl)-1-propenyl] benzoic acid (TTNPB), a very potent agent in carcinoprevention and carcinotherapy. Sixteen TTNPB conformations with close energy were obtained and characterized; four representative conformations were then studied for 14 derivative compounds, for which we found a substantial non-planarity of the two aromatic moieties. Large rotational flexibility of the arotinoid ring fragments was predicted by both methods. Very low barriers (0.4-3.9 kcal/mol) were found for the tetralenyl ring rotation. The two methods also agreed in predicting benzoic acid moiety rotation in a wide range of torsion angle values except those close to 0 or 180 degrees for which the PM3 rotational barriers were found to be considerably lower than the AM1 ones. This high conformational flexibility of arotinoid molecules may facilitate their favorable orientation in the process of fitting to the receptor sites.     

Inhibitory learning and memory in newborn rats

Firstly, the noetic value of the ontogenetic approach to the problems of learning and memory is emphasized; then the heterochrony and uneven time course of the development of neural systems are accentuated, which fully holds for the basic cognitive functions. Contrary to a broadly accepted opinion, that inhibitory learning develops later in the ontogeny, using a special method of passive avoidance (with gentle air flow inciting the new-born animal to move), the ability of new-born rats to learn an inhibitory reaction even several hours after delivery and remember it for 24 hr has been proven; special control experiments have excluded any possibility that it is a non-specific reaction. To get it, the specific features of the neonatal organism are to be considered and its functional capabilities not to be overlooked. This conditioned reaction as well as its 24 hr memory develops with a temporary reversal during several postnatal days, needing decreasing numbers of trials to meet the criteria. In the analysis of their mechanisms, it has been shown that adequate functioning of peripheral receptor zones providing afferent inputs from somatosensory areas of the conditioned stimulus is considerably involved in their establishment. Increased dendritic branching has been found in hippocampus and Meynert nucleus the following day after learning in the neonatal period. Special attention is devoted to the involvement of transmitters and/or modulators; the action of acetylcholine, noradrenaline, dopamine and nitric oxide has been discovered during the first postnatal hours; their application after meeting criteria displays a time and age dependent effect with a general characteristic of memory improvement. Neonatal learning under nitric oxide influence changes nitric oxide-synthase content in the brain. Increasing dopamine and nitric oxide availability in the brain improves both learning and memory, and their joint application positively alleviates these phenomena further. Dopamine and its D1 receptor agonists counterbalance decreased nitric oxide after nitric oxide synthase blockade; increased nitric oxide in brain and dopamine receptor antagonists similarly counterbalance each other.     

Isolation and functional analysis of alternative promoters in the human aquaporin-4 water channel gene

Levels of DNA damage in groups of 10 patients with insulin-dependent diabetes mellitus and 10 matched controls were compared using the comet assay; DNA strand breaks, oxidized pyrimidines (endonuclease III-sensitive sites) and altered purines (sites sensitive to formamidopyrimidine glycosylase) were measured. Mean values of strand breaks and oxidized pyrimidines were significantly higher in diabetics. Strand breaks correlated with body mass index in the diabetic group. A strong correlation was seen between formamidopyrimidine glycosylase-sensitive sites and serum glucose concentrations. When three patients with normal glucose levels were excluded from the statistical analysis, the mean value of formamidopyrimidine glycosylase-sensitive sites was very significantly elevated compared with normal. DNA damage in lymphocytes is thus a useful marker of oxidative stress, and in particular formamidopyrimidine glycosylase-sensitive sites seem to represent changes specifically related to hyperglycemia.     

Hippocampal and prefrontal cortex contributions to learning and memory: Analysis of lesion and aging effects on maze learning in rats.

Young adult rats with bilateral lesions to the hippocampus or prefrontal cortex, young operated controls, and normal old rats were tested on two complex mazes in the Hebb–Williams series. Approximately half the animals were previously trained on one of the mazes; the remainder received no previous training. The trained hippocampal rats showed sparing of memory for the general skill of maze learning but poor recall of the specific maze on which they had been previously trained. The opposite pattern was observed in trained prefrontal rats. In contrast, the aged rats' memory for maze-specific and maze-general information was impaired. The results confirmed the importance of the hippocampus for recalling highly specific information and pointed to a possible role for the frontal lobes in learning and remembering nonspecific skill-related information. The generalized deficit of the aged rats indicates that both types of memory were compromised and offers further evidence of frontal lobe and hippocampal dysfunction in normal aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Face learning and memory: The twins test.

The clinical utility of current face recognition tests has been questioned. To evaluate if a new paradigm may measure this type of memory more accurately, the authors created a novel test to examine face learning (previously uninvestigated) and short- and long-term retention. For this initial investigation of test sensitivity to hemisphere of dysfunction, patients with surgical resection from a temporal lobe and healthy subjects were tested. Recognition was evaluated on 3 trials: after a single exposure, after 4 exposures (for learning), and after a 24-hr delay interval. Patients with a right resection performed significantly worse than healthy controls and patients with left resection. There was no difference between patients with a left resection and controls. Classification of individual patients to side of resection based on test results showed higher sensitivity (82%) than published for other tests and maintained good specificity (79%). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Varieties of learning and memory in animals.

It is often assumed that there is more than one kind of learning—or more than one memory system—each of which is specialized for a different function. Yet, the criteria by which the varieties of learning and memory should be distinguished are seldom clear. Learning and memory phenomena can differ from one another across species or situations (and thus be specialized) in a number of different ways. What is needed is a consistent theoretical approach to the whole range of learning phenomena, and one is explored here. Parallels and contrasts in the study of sensory systems illustrate one way to integrate the study of general mechanisms with an appreciation of species-specific adaptations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determining the evolutionary potential of a gene

In addition to information for current functions, the sequence of a gene includes potential information for the evolution of new functions. The wild-type ebgA (evolved beta-galactosidase) gene of Escherichia coli encodes a virtually inactive beta-galactosidase, but that gene has the potential to evolve sufficient activity to replace the lacZ gene for growth on the beta-galactoside sugars lactose and lactulose. Experimental evidence, which has suggested that the evolutionary potential of Ebg enzyme is limited o two specific amino acid replacements, is limited to examining the consequences of single base-substitutions. Thirteen beta-galactosidases homologous with the Ebg beta-galactosidase are widely dispersed, being found in gram-negative and gram-positive eubacteria and in a eukaryote. A comparison of Ebg beta-galactosidase with those 13 beta-galactosidases shows that Ebg is part of an ancient clade that diverged from the paralogous lacZ beta-galactosidase over 2 billion years ago. Ebg differs from other members of its clade at only 2 of the 15 active-site residues, and the two mutations required for full Ebg beta-galactosidase activity bring Ebg into conformity with the other members of its clade. We conclude that either these are the only acceptable amino acids at those positions, or all of the single-base-substitution replacements that must arise as intermediates on the way to other acceptable amino acids are so deleterious that they constitute a deep selective valley that has not been traversed in over 2 billion years. The evolutionary potential of Ebg is thus limited to those two replacements.